For decision making, based on a map, the map has to be accurate or, at least, the accuracy has to be known. Accuracy assessment is an important part of any classification project. It compares the classified image to another data source that is considered to be accurate or ground truth data. Ground truth can be collected in the field. Other reference data can also be derived from interpreting high-resolution imagery, existing classified imagery, or GIS data layers.
In the context of the identification of marginal lands based on a developed GIS layer approach a suitable accuracy assessment needs to be performed. Therefore relevant techniques must be examined with regard to their applicability. The stratification of the sampling design will arise from the previous detection task for the marginal lands. Statistical methods have to be implemented.